The reactions of disulfides with alkylating agents and of thioethers with alkylthiolating agents will be studied for the purpose of preparing alkylthiosulfonium salts either as isolable compounds or as reactive intermediates. The propensity of alkylthiosulfonium salts to transfer an alkyl or an alkylthio group to nucleophiles will be explored using thioethers, amines, thioesters and alkenes and arenes as representative of sulfur, nitrogen and carbon nucleophiles. Alkylthiolation of bifunctional and polyfunctional nucleophiles such as allylic amines, sulfenamides, amino acids and peptides will be investigated in order to determine the initial site of alkylthiolation, the reaction products, and the extent of substrate rearrangement. The proposed work is based on previous results on this project which have revealed that C-S, S-S, and S-N bonds are rapidly cleaved, often with rearrangement, on alkylation or alkylthiolation at sulfur or nitrogen.